I agree with Ken. Yes, you can sue for specific performance. In California disputes over real estate contracts must be mediated first. Then other legal remedies such as arbitration or the courts can be utilized. The first question is “Why is the buyer backing out” The next should be “Have they cancelled the agreement within the time frame called for in the contract?"  Another question should be ” Is their reason for backing out justifiable withhin the context of the mutually written contract?“ I always like to ask if you as the seller have lived up to your end of the agreement. Have you fully and honestly disclosed all known defects regarding the property, the neighborhood, the taxes, future development, past or pending litigation, etc?

Once you have satisfactory answers to those questions I would proceed carefully. Have you discussed the situation with your broker if one is being used? Does your contract call for mediation or arbitration as opposed to the courts? If the buyer has breached the contract you would certainly be entitled to damages. I advise you to seek counsel from a qualified attorney who specializes in real estate contracts.

Good luck.